Week 8

Question 1

What are the different types of cell death?

Answer 1

Apoptosis (type I cell death), autophagic cell death (type II), and necrosis (type III)

Question 2

What is the difference between apoptosis and necrosis?

Answer 2

Apoptosis is described as an active, programmed process of autonomous cellular dismantling that avoids eliciting inflammation. Necrosis has been characterized as passive, accidental cell death resulting from environmental perturbations with uncontrolled release of inflammatory cellular contents.

Question 3

What is apoptosis?

Answer 3

A form of programmed cell death that occurs in multicellular organisms

Question 4

Can your own immune system kill you?

Answer 4

The innate immune system can also turn into our own worst enemy, when it becomes overactive or is tricked into attacking the body

Question 5

What is apoptosis essential for?

Answer 5

The generation of multicellular tissues during embryonic development as well as the maintenance of cellular homeostasis

Question 6

What mechanisms do T cells undergo?

Answer 6

Positive and negative selection in the thymic cortex and medulla, respectively

Question 7

Is apoptosis important to homeostasis?

Answer 7

Apoptosis is mainly active during embryonic development, when deletion of redundant cellular material is required for the correct morphogenesis of tissues and organs; moreover, it is essential for the maintenance of tissue homeostasis during cell life

Question 8

What is the role of apoptosis in vertebraes?

Answer 8

Apoptosis is important for proper development, maintenance of tissue homeostasis

Question 9

What is defective apoptosis associated with?

Answer 9

Many types of illness including autoimmune diseases, neurodegenerative diseases bacterial and viral diseases, heart diseases, and cancer

Question 10

What are the different type of necrosis processes in cells?

Answer 10

Necroptosis, pyroptosis, ferroptosis, and NETosis

Question 11

What are the signals of apoptosis?

Answer 11

Apoptosis is triggered when cell-surface death receptors such as Fas are bound by their ligands or when Bcl2-family proapoptotic proteins cause the permeabilization of the mitochondrial outer membrane

Question 12

What are caspases?

Answer 12

Orchestrating cellular destruction with proteolytic cascades

Question 13

What causes the inhibition of active caspases?

Answer 13

The inhibitor-of-apoptosis (IAP) family of proteins

Question 14

How is caspase-3 activated?

Answer 14

The cleavage of the interdomain linker and then subsequent cleavage of the N-terminal prodomain

Question 15

What is the caspase cascade?

Answer 15

Caspases are a family of cysteine proteases that act in concert in a cascade triggered by apoptosis signaling. The culmination of this cascade is the cleavage of a number of proteins in the cell, followed by cell disassembly, cell death, and, ultimately, the phagocytosis and removal of the cell debris

Question 16

What is apoptosis characterised by?

Answer 16

A series of dramatic perturbations to the cellular architecture that contribute not only to cell death, but also prepare cells for removal by phagocytes

Question 17

What orchestrates apoptotic cell death?

Answer 17

Members of the caspase family of cysteine proteases

Question 18

What do membrane alterations often trigger?

Answer 18

The recognition and engulfment of apoptotic cells by phagocytes

Question 19

What does apoptosis typically preclude?

Answer 19

The release of immunostimulatory molecules (called danger signals) that would not normally be present in the extracellular space

Question 20

What do effector caspases do?

Answer 20

An effector caspase (e.g., caspase-3) is activated by an initiator caspase (e.g., caspase-9) and the initiator caspase is activated via other PPIs

Question 21

What is iCAD?

Answer 21

A caspase-3 substrate that controls nuclear apoptosis

Question 22

What is phosphatidylserine?

Answer 22

A phospholipid that is abundant in eukaryotic plasma membranes

Question 23

What is the role of flippase?

Answer 23

Keeping PtdSer inside the cell, but PtdSer is exposed by the action of scramblase on the cell’s surface in biological processes such as apoptosis and platelet activation

Question 24

What is the role of phosphatidylserine once exposed on the cell surface?

Answer 24

PtdSer acts as an ‘eat me’ signal on dead cells, and creates a scaffold for blood-clotting factors on activated platelets

Question 25

What are the steps of cell clearance?

Answer 25

• migration of the phagocyte toward the proximity of the dying cells, -
• specific recognition and internalization of the dying cell -
• degradation of the corpse.

Question 26

What are ‘find-me’ signals?

Answer 26

Molecules released by a cell to attract phagocytes to that cell by chemotaxis, thereby increasing phagocytosis of the cell by phagocytes

Question 27

How is apoptosis detected?

Answer 27

Measuring the externalization of phosphatidylserine on the plasma membrane using fluorescent-tagged annexin V

Question 28

What is the role of the mitochondria in apoptosis?

Answer 28

Bcl-2 family members regulate the release of proteins from the space between the mitochondrial inner and outer membrane that, once in the cytosol, activate caspase proteases that dismantle cells and signal efficient phagocytosis of cell corpses

Question 29

What is in vitro assay development?

Answer 29

From Latin meaning in glass, in vitro assays are designed with components of cells that have been isolated to monitor biochemical and functional reactions to determine mechanism of actions and impact of novel therapeutics

Question 30

Is cytochrome c part of the apoptosome?

Answer 30

The apoptosome is a complex composed of cyt c, apoptotic protease activating factor-1 (Apaf-1), and deoxy adenosine triphosphate (dATP)

Question 31

Might cytochrome c be released from mitochondria
following induction of apoptosis?

Answer 31

During apoptosis induced by various stimuli, cytochrome c is released from mitochondria into the cytosol where it participates in caspase activation

Question 32

What is cytochrome c known to play a role in?

Answer 32

Electron transport chain and cell apoptosis

Question 33

When is cytochrome c released from the mitochondria?

Answer 33

During the early stages of apoptosis, although the precise mechanisms regulating this event remain unclear

Question 34

What is Apaf-1?

Answer 34

A critical regulator of apoptosis and a crucial part of the apoptosome that is assembled in response to several cellular stresses like hypoxia

Question 35

What does cytochrome c bind to in apoptosis?

Answer 35

Cytochrome c binds to inositol (1,4,5) trisphosphate receptors, amplifying calcium-dependent apoptosis

Question 36

What is Apaf-3?

Answer 36

A member of the caspase family, caspase-9

Question 37

What are the two required steps in apoptosome formation?

Answer 37

The dATP hydrolysis and exchange on Apaf-1

Question 38

What is assembly modelling?

Answer 38

A technology and method used by computer-aided design and product visualization computer software systems to handle multiple files that represent components within a product

Question 39

How is caspase 9 activated by the
Apoptosome?

Answer 39

Caspase-9 is activated by the Apaf-1 apoptosome. Apaf-1 contains a caspase recruitment domain (CARD) at its amino terminus, followed by a nucleotide-binding oligomerization domain (NOD) and 15 repeats of WD40 at its carboxyl terminus

Question 40

Is caspase-9 part of the apoptosome?

Answer 40

Procaspase-9 activation is mediated via its recruitment to a large protein complex called the apoptosome, comprising procaspase-9, APAF-1 (apoptotic protease activating factor-1), and additional regulatory proteins

Question 41

What does the intrinsic pathway of apoptosis involve?

Answer 41

A diverse array of non-receptor-mediated stimuli that produce intracellular signals that act directly on targets within the cell and are mitochondrial-initiated events